I have a spreadsheet with list of persons ("players"), and for a each person I have following values:

ID number (unique)

Name (just text)

Score from round 1

Score from round 2

...

Score from round 16

Now, I have this other spreadsheet I want to use for displaying results. Each row has these columns:

ID number

Name (fetched using ID from the Players-sheet)

First Round Eligible

Last Round Eligible

Score (sum of all rounds that are between First Round and Last Round).

I have problems calculating the score.
Example: I have ID "17", First Round "3" and Last Round "11". This means I need to to calculate sum of score through rounds 3 to 11 for player with ID 17. I can use vlookup to fecth the Name based on ID, but I don't know how to apply First & Last round to sum calculation.